At present, the video terminal market offers a variety of options, ranging from high-end professional devices to budget-friendly models. These solutions cater to diverse needs, from corporate video conferencing to personal usage.
In terms of video conference transmission, two main types of network environments dominate: circuit-switched networks like ISDN, DDN, and PSTN, and packet-switched networks such as ATM, IP, and Frame Relay. Each has its own set of advantages and limitations.
For individual users and small businesses, ISDN lines present a practical and cost-effective choice. ISDN provides end-to-end digital channels over the public telephone network, enabling voice and non-voice services. It can transmit video conferences at speeds from 384kb/s to 2Mb/s, charging per used B channel (64 kb/s). While ISDN is cheaper for low-traffic and short sessions, its reliability and stability lag behind dedicated lines due to ongoing upgrades across the national network.
Large enterprises often opt for DDN lines for superior video quality. DDN provides high-quality transmission, minimal latency, reliable circuits, and enhanced security. However, DDN's semi-permanent connection model, which maintains connectivity regardless of activity, makes it costly and unsuitable for brief communications. Instead, it’s ideal for long-term point-to-point or multipoint-to-point links. Multi-site DDN networks can be useful for connecting branch offices to headquarters, but the costs increase significantly if frequent inter-departmental communication is needed.
PSTN remains a viable option for individual users looking to experiment with video conferencing. Its widespread availability, affordability, and ease of use make it attractive. However, its low speed (56 kbps) and poor line quality limit its effectiveness for video conferencing, resulting in subpar image and sound quality.
ATM networks offer excellent video quality and flexibility, making them suitable for organizations requiring high-quality transmissions. ATM’s asynchronous transmission mode combines circuit-switching and packet-switching benefits, supporting multiple signal types and providing QoS guarantees. This approach is ideal for units needing both quality and reliability but comes with high equipment costs and the need for an ATM network infrastructure.
IP networks represent the simplest and most cost-effective access method. Using packet-switching techniques, these networks prioritize flexibility and affordability, particularly for broadband environments like ADSL and FTTB+LAN. While IP networks offer good cost efficiency, their reliance on best-effort delivery compromises real-time communication quality compared to dedicated lines. Nevertheless, their popularity among small and medium-sized businesses continues to grow.
Satellite networks excel in mid- and long-distance video conferencing, offering broad coverage, high speeds, and strong security. They are particularly beneficial for remote locations and multinational corporations. However, satellite solutions are expensive, requiring significant investment in ground stations and satellite channels. Additionally, the inherent delay makes them less suitable for high-real-time-demand systems.
Frame relay networks provide another professional-grade option, primarily for data services. These networks are efficient, offer high throughput, and have low latency. Despite being costly, they deliver excellent video quality, making them suitable for specific business needs.
When purchasing video conferencing terminals, users should consider product audio-visual effects, application requirements, and system environment. Hardware solutions typically outperform software-based alternatives in terms of decoding efficiency and compatibility across multiple network environments.
Users must also evaluate their application environment and needs. Blindly following trends without considering practical requirements can lead to unnecessary expenses. To maximize value, buyers should adhere to several principles: define clear purposes, ensure compatibility with existing equipment, prioritize product quality and after-sales support, and consider the vendor’s technical expertise and networking experience.
By balancing these factors, users can select the optimal video conferencing solution tailored to their unique circumstances.
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